The Birds of Rathlhi Island, Co. Antrim. 53 



accessible cliff. The Peregrine's eggs were wanted by a collector, 

 and some boys, watching the birds away from the nest, went down on 

 a rope, and took the eggs. The birds on their return, finding their 

 nests empty, attacked the Ravens, killed the hen, and demolished the 

 nest. The cock Raven fought fiercel}^, but was at last overcome by 

 the Peregrines, who forsook that particular locality, and never re- 

 turned. Up to this time both families had lived in apparent friend- 

 ship, not interfering with each other, but it was evident the Ravens 

 were blamed for the theft. The fight was witnessed from the top of 

 the cliffs by many who were attracted by the cries of the birds, and 

 they described it as being most bloody and determined. 

 *Corvus cornix, Iv. — Hooded Crow. Very common; frequents the 

 beach of Church bay and elsewhere. Breeds in the cliffs. 

 Corvus frugilegus, L. — Rook. Young and old birds sometimes seen 

 in autumn and winter. Observed by light-keepers on migration. 



(TO BE CONTINUED.) 



COUNTY DUBININ, PAST AND PRESENT. 



BY PROF. GRE)NVII.I.E: A. J. COI,K, F.G.S. 



{Continued from page 36.) 



III. — Thk Granite Chain. 



Thk remarkable volcanic activity at the close of the Ordovician 

 period was the herald, in Ireland, of great changes in the 

 relations of sea and land. The shocks of earthquake and the 

 fierce explosions from volcanic isles were in reality minor 

 matters compared to the slow uplifting of the sea-floor, the 

 bending and contortion of the Ordovician shales and lime- 

 stones (fig. 4, p. 32), and the formation of. the great chain 

 of hills which even to-day forms the S.E. frontier of the 

 country. We are only slowly beginning to understand the 

 causes of these wide earth-movements ; sufiice it that, after 

 the conversion of a great part of the area of the British Isles 

 into dry land, and the consequent excavation of its surface by 

 rain and rivers, the sea was again allowed to flow in over 

 England, Wales, and western Ireland, depositing strata known 

 as the Silurian system. But in Co. Dublin the elevation 

 seems to have been more permanent ; along an axis stretching 

 far into the south, the strata formed a sort of arch, their 

 upheaval allowing of molten rock to ooze up from lower 

 levels of the earth's crust, following, inch b}^ inch, the upthrust 

 of the beds, and finally consolidating beneath them as a dense 

 and crystalline mass. 



How far this once molten rock extends beneath the present 

 surface it is quite impossible to say; but denudation has 

 already reached down to it through its former Ordovician 

 covering at such outlying points as Rockabill ' on the north 



' First noted by Mr. C. W. Hamilton in 1840, see G. S. D. ii., 138. 



